package org.bouncycastle.asn1;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * DER TaggedObject - in ASN.1 nottation this is any object proceeded by a [n] where n is some number - these are assume to follow the construction
 * rules (as with sequences).
 */
public class DERTaggedObject extends ASN1TaggedObject {
    /**
     * @param tagNo
     *            the tag number for this object.
     * @param obj
     *            the tagged object.
     */
    public DERTaggedObject(int tagNo, DEREncodable obj) {
        super(tagNo, obj);
    }

    /**
     * @param explicit
     *            true if an explicitly tagged object.
     * @param tagNo
     *            the tag number for this object.
     * @param obj
     *            the tagged object.
     */
    public DERTaggedObject(boolean explicit, int tagNo, DEREncodable obj) {
        super(explicit, tagNo, obj);
    }

    /**
     * create an implicitly tagged object that contains a zero length sequence.
     */
    public DERTaggedObject(int tagNo) {
        super(false, tagNo, new DERSequence());
    }

    void encode(DEROutputStream out) throws IOException {
        if (!empty) {
            ByteArrayOutputStream bOut = new ByteArrayOutputStream();
            DEROutputStream dOut = new DEROutputStream(bOut);

            dOut.writeObject(obj);
            dOut.close();

            byte[] bytes = bOut.toByteArray();

            if (explicit) {
                out.writeEncoded(CONSTRUCTED | TAGGED | tagNo, bytes);
            } else {
                //
                // need to mark constructed types...
                //
                if ((bytes[0] & CONSTRUCTED) != 0) {
                    bytes[0] = (byte) (CONSTRUCTED | TAGGED | tagNo);
                } else {
                    bytes[0] = (byte) (TAGGED | tagNo);
                }

                out.write(bytes);
            }
        } else {
            out.writeEncoded(CONSTRUCTED | TAGGED | tagNo, new byte[0]);
        }
    }
}
